Being direct is always the best while still remaining professional. Having said that, sometimes ignoring these kind of people works too.

We have a new also a very annoying employee, it’s only her second year with us, she is extreme case of brown noser and “know it all.” She is sugary sweet fake and very manipulative. Most of us were on to her early on. I am her mentor so when it comes to day to day tasks she listens. But other stuff she likes to tell us how to do things and she likes to gossip and bad mouth people, and she is new!

My routine response to her is “it’s not how we do things.” Then I follow with explanation how we do things: like we don’t undermine others or overstep our authorities. I also told her directly “stop passing information around, no need to tell so and so when so and so said things”. She always finds excuses why she gossiped or why she tries to boss people around

Someone has to put this girl into her place. Or you can just nod and ignore